Weight and size are usually a lot more important for engineers developing batteries and other components of mobile gear – laptops, phones and other smart(ish) electronics.
Color turns out to be really important as well, at least if the color is "transparent."
Materials scientists at Stanford have developed prototypes of transparent batteries that can be combined with transparent monitors, transistors and other components that have already been built using transparent materials or designs, to make an incredibly expensive, completely impractical set of mobile devices that are far easier to lose than anything available today.
Materials science professor Yi Cui led the research, which focused on making all the components of the battery as thin as possible to make them easier to see around, if not completely through.
Very thin electrodes don't usually hold much electricity, so Yi Cui wove the very thin electrodes into a very fine mesh with lines only 50 micrometers wide, making them largely invisible.
Presumably even a transparent phone or laptop would be mostly visible, and the screen would display pictures that would make the whole unit more visible yet. So the benefit is more a design or appearance issue for when the device isn't being used or has simply been put down.
Luckily, Murphy's Law of Expensive Gadgetry being what it is, even putting an expensive, transparent gadget down won't make it difficult to find. It will be the crunch under your foot when you walk or on your chair when you sit down suddenly.
Smartphone engineers had to develop a phone-home feature to make their stuff that easy to find. The Stanford team is way ahead of the game, if it can keep from losing the ball.